Blenko has always identified each design it produced with a unique number. To authenticate an item as Blenko one must be able to match the shape to a corresponding design number shown in a catalog. Following is an explanation of the three different numbering systems The Blenko Glass Company used.

About "Experimental" Items With No Design Number:
Beware! Each year Blenko produced new designs to add to the line, a small number of items, about 5 at most, were rejected each year for a variety of reasons (cost, difficulty to produce, marketability, aesthetic shortcomings, etc). Commonly two prototypes, only occasionally more, were made of these rejected designs and then sold in the Visitors' Center (or its precursor). Noteably many of these items were made by using old molds for the initial form and so bear a resemblance to other designs. "Exprimental" items are best avoided unless accompanied by convincing documentation as their authenticity and relevance will otherwise always be highly questionable at best.

Most items people call "experimental" Blenko (aka 'one-offs', 'end of day', 'whimsies', 'lunch hour specials' etc) are almost always another company's product that the owner can not identify; the famous example is on p.83 of Schiffer's book "Blenko Cool", first ed., which identifies a Zeller vase as "experimental Husted." Similarly, p.40 of the second edition inexplicably identifies the quite common 5831 from Blenko's standard line as "experimental."

Numbering System Prior to 1948
There is currently no evidence published to conclusively indicate how design numbers were assigned in this period, though similar designs or variations often appear in series.

The numbering system does not correlate to the post-1953 system in terms of the first two numbers indicating year - at the very least if that system was used it was not used exclusively or consistently. As such one can not infer that, for example design #3724 was designed in 1937. It is however, reasonable to assume, but by no means assured, that pre-1948 design numbers may roughly indicate chronological order as they may have been applied sequentially.

In some instances the pre-1948 system conflicts with the post 1953 system. For example #517 was designed circa 1940's. However, such conflicts are rare.

Numbering System 1948 to 1953
During Winslow Anderson's tenure, design numbers are primarily designated with the "900" series (from #900 to #999). While the "900" series constitutes the majority of Anderson's designs, he did produce more than 150 new designs, including such items as the #497 bar set series, the #19 series of florifom plates, and almost all "53" series designs.

Interestingly, Anderson did not claim either the "600" or "800" series as his and they do appear to predate his tenure in the catalogs, this corroborates Anderson's claim that he was not responsible for devising the "900" series system and that method was in use prior to his tenure.

Numbering System 1953 to 1974
In 1953 Blenko adopted a system that stayed in place until 2002: design numbers are either 3 or 4 digits in length. The first two digits indicate the year the design was introduced (ex: 5310 was designed in 1953). The one or two digits after the first two have no significance other than to serially distinguish designs. It is important to note that it is not true, for instance that #552 was necessarily designed after #551; rather, they were simply assigned numbers in that order and the designation was usually not made by the designer.

Letters On Design Numbers
Letters following design numbers most commonly indicate size; X, S, M, L, LL (extra small, small, medium, large, extra large).

Other uses of letters include:
- in early items, letters indicate ornamentation or style, ex: "L" at the end can indicate that "leaf" decorations are added to a shape, "B" at the beginning indicates controlled bubble
- on barware letters designate function, ex: CT= cocktail, HB = highball
- distinguish versions of designs in a series as in 65A, 65B, 65C, 65D

1953 catalog page showing the last design of the "900" series; the 999 ship's decanter

1953 catalog page showing the early use of the new numbering system

1955 catalog page showing the use of letters "L, M, & S" designating the different sizes of design 5519

The only universal and official way to identify a Blenko design is by its number. However, some descriptive or allegorical names were printed in the catalogs alongside the design numbers. After and including the year 1960, Blenko catalogs contained no names or descriptive terms, identifying items exclusively by their design number and dimensions; therefore no post-1959 design has an official name. Below are 12 of the most memorable official Blenko design names.

917 Patio or Terrace Vase (refers to function Anderson intended)	918 Patio or Terrace Vase (refers to function Anderson intended)	949L Indented Aquarium Vase
905 Swish-It Mix-It Pitcher (refers to instructions for use)	968 Chianti Decanter	534 (& 535, not shown) Pouch Vase
5427 Gurgle Bottle (onomatopoeic; refers to imagined sound of a liquid poured from it)	552 Portrait Vase	5720 Napoleon Decanter (stopper reminded Husted of Napoleon's hat)
5730 Accents	587 Spool Decanter	5931 Doughnut Decanter

Following is a full list of official and memorable names & description found in Blenko catalogs, in chronological order.

Anderson Designs

903-2; Small Two-Dent Vase

903-4; Small Four Dent Vase

905; Swish-It Mix-It Pitcher

910-2; Large Two Dent Vase

910-4; Large Four Dent Vase

917; Patio Vase or Terrace Vase

918; Patio Vase or Terrace Vase

921; Dented Free-Form Vase

938; Double Dish

942; Ribbed Free-Form Vase

949; Spherical Dented Free-Form Vase

949L; Indented Aquarium Vase

955; Asymmetrical Bowl

956; Chalice Vase

961; Flat-Sided Vase

964; Horn Vase

965; Candleholder Goblet

966; Free-Form Ashtrays

967; Flat-Sided Pitcher

968; Chianti Decanter

971; Fish Vase

980; Globular Vase

986; Rosette Vase

992; Steer Head Wall Vase

995, 996 & 997; Utility Jars

999; Ships Decanter

532; Pear Vase

533; Four Sided Bud Vase

534; Small Pouch Vase

535; Large Pouch Vase

537; Free Form Dish

Husted Designs

541; Diamond Vase

5410; Bird Bottle Vase

5420; Primitive Motif Triangular Decanter

5421; Large Blown Out Decorations Vase

5422; Small Blown Out Decorations Vase

5427; Gurgle Bottle

551; Flattened Abstract Button Vase

552; Portrait Vase

556; Horse Motif Button Vase

557; Decorative Utility Jar

558; Asymmetrical Sculptured Form

559; Cat Vase

5510; Kitty Decanter

5510L; Cat Decanter

5518; Pressed Horse Motif Vase

562; Wedge Cut Decanter

563; Mushroom Decanter

571; Ice Tea Pitcher

572; Tall Spouted Decanter

5719; Large Mushroom Decanter

5720; Napoleon Decanter

5725; Ultilidecanter

5727; Tall Goblet Vase

5730; Accents

5732; Mermaid Decanter (NB: due to a typo the catalogue reads "Mermaidecanter")

5739; Rooster Decanter

587; Spool Decanter

5812; Hurricane Shade

5825; Twist Decanter

5830; Owl Vase

5931; Doughnut Decanter

5835; Twisted Vase

5933; Oval Decanter

5916; Reversible Candlestick-Vase

5927; Reversible Bowl

Common use names are those that are given by collectors. We are of the opinion that if a design already has a serviceable official catalogue name it is inappropriate to re-name it. Evocative, poetic or allusive names are the sole prerogative of the designer (ex: Napoleon decanter, Gurgle decanter), others are best left to applying brief and accurately descriptive terms as names that effectively recall the design rather than inventing interpretive ones.

Anderson Designs

920; teardrop decanter

948; bent-neck decanter

536; tripod bowl

538; crimped rose bowl

Husted Designs

545; fish medallion bowl

555; tab-handled martini pitcher

556; horse medallion vase (official name "Applied Horse Motif Button Vase")

557; double portrait jar, also "anniversary jar" as Husted says he designed it in recognition of his second anniversary (official name "Decorative Utility Jar")

558; high-heel bowl (official name "Asymmetrical Sculptured Form")

5518; impressed horse vase (official name "Pressed Horse Motif Vase ")

563; small barbell decanter (official name "Mushroom Decanter")

5610; form-handled pitcher (a useful revisionist name give by Husted)

5611; tall tab handled pitcher

5615; star medallion vase

573; spouted martini decanter

5711; bell-footed pitcher

5716; bamboo vase

5917; large barbell decanter (official name "Large Mushroom Decanter")

581, 582 & 583; Echoes series chalices (a revisionist Husted name)

584 & 585; pierced handled pitchers

5812; cut-out hurricane

5815; Minaret decanter (the name Husted recalls giving it at the time of design)

5819; double pierced bowl

5820; single pierced bowl

5831; tri-colored bowl

5832; three-part epergne

5833; two-part epergne

595; polkadot vase

597; tri-cornered blobs vase

599; long split-bottle bowl

5910; round split-bottle bowl

5915; U-cut cinched waist vase

5925; pinched cylinder vase

5929; balustrade decanter or profile decanter

5933; oversized perfume decanter (official name: Oval Decanter)

5937; tall cone-stopper decanter

5942; U-cut cylinder vase, also; "Glass 1959" vase

605; gemstone decanter

6024 & 6025; rocket vase

6027; shot glass stoppered decanter, Note: according to Husted this was NOT designed to be a shot glass and he never saw it as such

6111; cog decanter

6134; ram's head vase

6145; rooster bowl

6212; flame stoppered genie decanter

6217; fish decanter

6218; sun-face decanter or Omnibus decanter (a name given by Husted as his inspiration was the logo for a television show called Omnibus)

6314; tall surrealist decanter

6315; square surrealist decanter

6316; long surrealist decanter

Myers Designs

6427; stretched bottle

Gump's Decanter

6520; soldier vase

6525; lady decanter

6527; butterfly decanter

6615; spinning top decanter

6712; constricting coil vase

6713; constricting coil decanter

6721; finial lidded jar

6732; elaborate balustrade decanter

6820; tendril decanter

7016; sheriff decanter

7022; mushroom stopper decanter

7041; cone footed chalice

7043; cone footed ball vase

7047; lady vase